The following illustrates the effect of vitamin B6 on Parkinson’s disease-like symptoms. Nothing written on this page should be interpreted to mean that vitamin B6 has any effects on Parkinson’s disease.

CDC data:

1958-1975 the Parkinson’s disease death rate decreased

1976-present the Parkinson’s death rate increased by 390%

WARNINGS --- Carbidopa has no antiparkinsonian effect

Carbidopa Ineffective

Our Position

We are not claiming that we have published a study definitively showing carbidopa caused the 328.7% increase in the Parkinson’ death rate between 1976 and 2011. We have published a hypothesis to serve as a starting point to study this problem. Consider the following example:

The Facts:

89% of Parkinson’s disease patients take a combination pill containing carbidopa. This approach does not use carbidopa.

Carbidopa binds irreversibly to and permanently deactivates vitamin B6 and vitamin B6 dependent enzymes. 1,2

Carbidopa Paper #1  Carbidopa Paper #2

Carbidopa can deplete vitamin B6. 3,4,5

Depletion Paper #1  Depletion Paper #2  Depletion Paper #3

Vitamin B6 depletion increases the death rate when all causes are considered as a group. 6,7

B6 Death Rate Paper #1  B6 Death Rate Paper #2

The Bottom Line:

• Carbidopa depletes vitamin B6, when on an optimal diet this represent B6 relative nutritional deficiency
• Vitamin B6 depletion causes an increased death rate
• The next question for the study is, “Does carbidopa increase the death rate?”

CDC-Death-RateFigure 1 - Center for Disease Control data: Between 1958 and 1975 there was no carbidopa, only L-dopa was available. The Parkinson’s death rate dropped.





CDC Death Rate 2Figure 2 - Center for Disease Control Data: As published in the carbidopa B6 death paper, between 1976 (the first full year of carbidopa sales) and 2011, the Parkinson’s death rate increased by 328.7%. Currently, between 1976 and 2014 (the most recent CDC data point) the Parkinson’s death rate has increased by 390%.

Read the CARBIDOPA B6 DEATH PAPER as posted
on the National Institute of Health website

8 Hinz, M. Et. Al. The Parkinson's disease death rate: carbidopa and vitamin B6. Clin Pharmacol. 2014 Oct 21;6:161-9

The first step in solving a problem is defining what the problem might be.

A hypothesis is a starting point for scientific studies. The carbidopa B6 death paper documents the purposed hypothesis, it reads:

  • The hypothesis: “Systemic vitamin B6 concentrations inversely correlate with mortality induced by coronary artery disease, colorectal cancer, stroke, heart failure, and atherosclerosis. We hypothesize that if carbidopa and benserazide significantly deplete PLP (vitamin B6), then an increased death rate will be observed.”

  • The paragraph goes on to note: “During the first 15 years of prescribing L-dopa (1960–1975) it was administered without carbidopa, a practice that was associated with a decreasing death rate. On May 9, 1975, the US FDA approved carbidopa for concomitant administration with L-dopa. Between 1976 and 2011, there has been an increase in the general Parkinson’s disease death rate.”


Barlette, M. Biochemistry of the Water Soluble Vitamins: A Lecture for First Year Pharmacy Students American Journal of Pharmaceutical Education 2003; 67 (2) Article 64

Diadone, F. Et. Al. Identification by Virtual Screening and In Vitro Testing of Human DOPA Decarboxylase Inhibitors PLoS ONE 7(2): e31610. doi:10.1371/

Carbidopa Binds Irreversibly Paper #1

Carbidopa Binds Irreversibly Paper #2

3 Airoldi, L. Et. Al. Effect of Pyridoxine on the Depletion of Tissue
Pyridoxal Phosphate by Carbidopa Metabolism, Vol. 27, No. 7 (July), 1978

4 Yee, R. Blood-brain barrier and neuronal membrane transport of 6-[F] fluoro-L-dopa Biochemical Pharmacology Volume 62, Issue 10, 15 December 2001, Pages 1409–1415

5 Bender D. Et. Al. Nonnutritional uses of vitamin B6. British Journal of Nutrition,1999 81, pp 720

Depletion Paper #1  Depletion Paper #2  Depletion Paper #3

6 Hang, YC Et. Al. Prediction of all-cause mortality by B group vitamin status in the elderly. Clin Nutr. 2012 Apr;31(2):191-8. doi: 10.1016

7 Zhao, L. Et. Al Prospective cohort studies of dietary vitamin B6 intake and risk of cause-specific mortality Clinical Nutrition May 8, 2018 1-8

B6 Death Rate Paper #1  B6 Death Rate Paper #2

Other Carbidopa Depletions, Consider The Following:

Carbidopa is known to induced niacin deficiency (vitamin B3). The enzyme which metabolizes tryptophan to niacin is a B6 enzyme.

Niacin Depletion Paper #1  Niacin Depletion Paper #2

Higher dopamine levels decrease the severity of Parkinson’s disease-like symptoms. Depletion of vitamin B6 and B6-dependent enzymes can compromise the metabolism of L-dopa to dopamine by the B6 enzyme AADC, which can induce Parkinson’s disease-like symptoms which may be identical to Parkinson’s disease symptoms getting worse as dopamine synthesis collapses secondary to vitamin B6 deficiency. Read the AB Baker, MD paper from 1941:

1941 Paper from AB Baker, MD

Depletion of vitamin B6 is known to occur with carbidopa and Parkinson’s disease. These are two of the 29 causes of relative nutritional deficiency that can occur in Parkinson’s disease patients while taking carbidopa with L-dopa.

ABSTRACT, The 29 Potential Parkinson-relative Nutritional Deficiency Causes

Histamine synthesis is dependent on two vitamin B6 enzymes. Carbidopa induced vitamin B6 relative nutritional deficiency can induce antihistamine dyskinesias. 

Click below to read our dyskinesia paper posted on the National Institute of Health website. 

Our Dyskinesia Work Documented